Plant Nutrition: Photosynthesis
6.1 Photosynthesis
Definition
- Process by which plants make carbohydrates (glucose) from raw materials using light energy.
- Takes place in chloroplasts (contain chlorophyll).
Chlorophyll
- Green pigment in chloroplasts.
- Absorbs light energy and converts it into chemical energy.
Uses Of Carbohydrates Made In Photosynthesis
| Product | Use |
|---|---|
| Starch | Storage form of energy in plants |
| Cellulose | Builds plant cell walls |
| Glucose | Used in respiration for energy |
| Sucrose | Transported in phloem to other parts of plant |
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Equations For Photosynthesis
- Word Equation:
Carbon dioxide + Water → Glucose + Oxygen (in presence of light and chlorophyll). - Balanced Chemical Equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Investigations
- Test leaf for starch → boil, treat with ethanol, iodine turns blue-black if starch present.
- Use plants with/without chlorophyll (variegated leaves).
- Light and CO₂ experiments with covered/uncovered leaves.
Limiting Factors
- Light intensity.
- CO₂ concentration.
- Temperature.
- If one is below optimum → slows down photosynthesis.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course